Goose down and eider down are generally regarded as the best materials available for insulating coverings. This is largely because their bulk densities are extremely low (i.e., about 0.2 lbs./ft..sup.3), and they are sufficiently porous to allow the escape of water vapor from the surface of the body. This ability to "breathe" is an extremely important feature in the context of body coverings, because it allows the escape of perspiration which otherwise would accumulate and detract from both insulation and comfort if the covering were totally impervious. Thus, while some materials, such as closed-cell plastic foams containing high molecular weight gases entrapped in the foam cells, have greater insulating power per unit of thickness than goose or eider down, they are heavier and are not suitable for body coverings because they do not "breathe".
Goose and eider down, however, have several serious drawbacks. They are very expensive (i.e., about $24/lb. wholesale). Also, they totally lose effectiveness when they become wet, and, once wet, they are extremely difficult to dry. They could, of course, be packed in a totally waterproof envelope, but, if that were done, the required breathability of the covering would be lost. If the envelope were totally impermeable to water and air, it would then be impossible to pack the down-insulated envelope into a small volume when not in use. The compressibility of goose down when not in use, accompanied by recovery of loft when the pressure is released, is a very important property of goose down.
Accordingly, a primary object of the invention is to provide improved insulation for items such as body coverings which, at one and the same time, enjoys the insulating and breathability and compressibility advantages of goose or eider down, but substantially overcomes the disadvantages of wetability thereof. An object is to provide a process for making such articles. An additional object is to improve the insulating power of articles employing water fowl down without increasing the bulk density when they are being used. A further object is to accomplish the foregoing without increasing the discomfort of the user. Still another object is to provide an insulating article according to the above objects which also is adapted to be compressed when not in use.